Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) - USD ($) $ in Thousands |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|---|---|---|---|
| Derivatives, Fair Value [Line Items] | ||||||
| Available-for-sale securities, at fair value | $ 19,293,354 | $ 21,220,819 | ||||
| Mortgage servicing rights, at fair value | 1,450,261 | $ 1,301,023 | 1,086,717 | $ 898,025 | $ 747,580 | $ 693,815 |
| Interest-Only-Strip [Member] | ||||||
| Derivatives, Fair Value [Line Items] | ||||||
| Available-for-sale securities, at fair value | $ 146,888 | $ 117,826 |
| X | ||||||||||
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|